#include<stdio.h>
unsigned long long fib_r(unsigned long long n){
    if (n<=0) n=1;
    switch (n)
    {
    case 1:
    case 2:
        return 1;
    default:
        return fib_r(n-1)+fib_r(n-2);
    }
}
int main(){
    unsigned long long n=100;
    double g=(double)fib_r(n)/fib_r(n+1);
    printf("%.8f",g);
    return 0;
}